Justification:Amphibolis griffithii is endemic to southern Australia. The overall population size is thought to be stable. There are no major threats other than localized coastal development. This species is listed as Least Concern.

Based on two studies on Amphibolis griffithii from the Global Seagrass Trajectories Database, there was an average of 0.8% decline per annum between 1990 and 2000. The population is thought to be overall stable.

In the sub-littoral zone, Amphibolis griffithii may form extensive beds on sandy floors, sand covered rocks, gravel bottoms and, less frequently, on banks of firm, compact clay in places where the water is kept continually in motion by currents or wave action. Plants of the genus Amphibolis are dioecious and viviparous (Ducker et al. 1977). The considerably smaller range of this species compared to A. antarctica suggests a limited temperature tolerance (Ducker et al. 1977).

Amphibolis griffithii has no known major threats. There may be some localized threat from human activities such as port and industrial development, pipelines, communication cables, mining and dredging. Seagrass losses may be attributed to dredging of the Fremantle Port Authority shipping channel, shell-sand dredging, eutrophication, and movement of large sand sheets (Kendrick et al. 2000).

Cockburn Sound, an area in the range of Amphibolis griffithii, has been subjected to steady degradation since 1954, with the establishment of an oil refinery and the successive establishments of steel works, fertilizer factories, sewage-treatment facilities, and a power station. This has lead to contaminated effluents and increased nutrient loads in the surrounding waters. Between 1954 and 1978 the seagrass meadow in this region decreased from 4,200 to 900 ha and leaf detritus production was reduced from 23,000 to 4,000 t (dry weight)/year. Seagrasses in this region include Posidonia sinuosa, Posidonia australis, Posidonia coriacea, Halophila ovalis, Halophila decipiens, Syringodium isoetifolium, Zostera tasmanica, Amphibolis griffithii, and Amphibolis antarctica (Cambridge and McComb 1984).

Cambridge, M.L. and McComb, A.J. 1984. The loss of seagrasses in Cockburn Sound, Western Australia. I. The time course and magnitude of seagrass decline in relation to industrial development. Aquatic Botany 20: 229-243.

Kirkman, H. and Walker, D.I. 1989. Regional studies - Western Australian seagrass. In: A.W.D. Larkum, A.J. McComb and S.A. Shepherd (eds), Biology of Seagrasses. A treatise on the biology of seagrasses with special reference to the Australian region, pp. 157-181. Elsevier, Amsterdam.